examples of use of climatic model on the design of flexible … 8 - site... · california bearing...

Claudia E. Zapata Assistant Professor

Examples of Use of Climatic Model on the Design of Flexible Pavements

2013 Seminar International Civil Aviation Organization ICAO South American Regional Office

Lima, Peru– August 6th-9th , 2013

Agenda

Study 1 Estimation of moisture profile for the Port of Long Beach

Study 2 Estimation of moisture content under airfields Study 3

Impact of site location and groundwater table depth on the thickness of airfield pavements

Overview

In the past, the majority of structural designs for highway and airfield pavements have been developed considering saturated conditions for unbound material layers Variety of environmental locations and groundwater table (GWT) conditions

Overview

Unsaturated soil mechanics coupled with site environmental conditions has not been implemented in airfield pavement analysis by the practicing community The variations of environmental locations, GWT depth and site soil properties have a significant impact on structural design of highway and airfield pavements

study 1 Estimation of moisture profile for the Port of Long Beach

Overview

Independent assessment of the Main Harbor Terminal pavement designs for the port of Long Beach (California)

Project objectives

Assess economic predictions of alternative designs

Maintain performance with lowest possible costs in life cycle

Reduce pavement construction costs

Proposed MHT layout and design area locations

Wharf Area (Area 1) No Design Work

Waterside Traffic Area (Area 2)

Waterside Transfer Area (Area 3)

Container Yard Stacking Area (Areas

4a and 4b)

Landside Transfer Area (Area 5)

Landside Traffic (Area 6)

Landside Roadway (Area

7) Landside

Traffic (Area 8)

Intermodal Yard Wheeled

Buffer Area (Area 9)

Non-ASC Storage Area

(Area 10) RMP

(Area 11)

Estimation of the Thornthwaite Moisture Index

Variable Mean Variance Standard Deviation

Precipitation (in.) 30.2 185.8 13.6

Annual Heat Index 80.7 5.9 2.4

Potential Evapotranspiration 77.8 9.8 3.1

Thornthwaite Moisture Index -35.7 178.1 13.3

Estimation of the Thornthwaite Moisture Index

Monte Carlo Simulation Condition Number of Simulations: 25,000 Location: Long Beach, CA Weather Station: Long Beach Daugherty Field

Airport Latitude: 33.5° Longitude: -118.1° Elevation: 37 ft = 11 m

Current degree of saturation

0

5

10

15

20

25

0 20 40 60 80 100

Dept

h (ft

)

Degree of Saturation (%)

Boring 1

Boring 2

Boring 3

Boring 4

Boring 5

Boring 6

Boring 7

Average

Theoretical degree of saturation at equilibirum vs. current degree of saturation

0.05.0

10.015.020.025.030.035.0

0 20 40 60 80 100 120

Dept

h (ft

)

Degree of Saturation (%)

Theoretical S% at Equilibrium

Current S%

Final design CBR and Mr

Depth Mr Design CBR

Surface to -5’ E = 18,000 psi 20%

-5’ to -7’ E = 15,000 psi 15%

-7’ to -16’ E = 11,000 psi 9.5%

> -16’ E = 8,000 psi 6%

Final design subgrade stiffness

Equivalent Foundation Reaction Modulus (for Rigid Pavement)

ksg = 141 pci

Equivalent Foundation Resilient Modulus (for Flexible Pavement)

Esg = 15,000 psi

California Bearing Ratio CBRsg = 15

Major findings / benefits to the POLB

The use of the state-of-the-art technology of unsaturated soil mechanics clearly demonstrated and was verified by field results that Design Equilibrium Strength of Subgrade foundation should not be based upon saturated (soaked) soil strength tests.

Major findings / benefits to the POLB

Use of “Soaked Samples” are quite conservative in the Los Angeles basin area, where negative Thornthwaite Moisture Indices show overall tendencies of soils to be in a “suction behavior mode”

This will lead to the design of much thinner (and cheaper) pavement cross sections that would be actually needed for the performance period

Historic strength data used at the port was based on a soaked CBR design value of 8.

The use of unsaturated soil properties allowed for the final design CBR to be increased to a value of 15.

Early computations indicated that cost savings of $5-$10 million could be achieved for the approximate 1 million square feet of pavement to be required

study 2 Comparison of actual field measured moisture contents to theoretically predicted moisture

To study the feasibility of using the environmental models to estimate moisture content distribution under airfields

Study done for the USAF by Zapata and Cary (2012)

11 airfields

734 water content measurements October 1945-November 1952 Structure and materials properties

obtained from reports Climatic data files (HCD) generated

from NCDC historic records Results from about 140 M-EPDG runs

Data from 4 different locations and different depths below runway and taxiway pavements

(a)

Site properties GWT Avg.Ann. Temp. Airfield

No Airfield Airfield Zone AC Depth Rainfall Range ElevationName Location Class (in) (in) Type PI P200 (in) Type PI P200 Type PI P200 Type PI P200 (ft) (in) (F) (ft)

1 Kirtland AFB Albuquerque, NM Arid L1 2 8.5 SC 4 10 SC 7 29 SC 4 31 >100 7 104 to -10 5000

L2 SC 4 10 SM 5 - SM 4 -

L3 SC 4 3 SM NP 30 SC 5 32

L4 SC 3 35 SC 4 34 SC 6 36

2 Santa Fe MA Santa Fe, NM Semi-arid L1 3 8.5 GC 15 25 CL 21 52 SC 24 35 >100 10 97 to -13 6000

L2 GC 11 14 SC 18 38 SC 27 25

L3 GC 13 18 SC 19 36 SC 21 30

L4 CL 17 54 CL 10 - CL 10 -

3 Clovis AFB Clovis, NM Semi-arid L1 1.5 12 SC 6 24 CL 9 50 CL 14 45 >100 15 109 to -11 4100

L2 SC 7 33 CL 17 44 CL 12 44

L3 SC 7 27 CL 16 44 CL 10 44

L4 SC 8 - CL 13 - CL 8 -

4 Bergstrom AFB Austin, TX Dry L1 2 9 GM 1 14 2 to 4 CL 7 41 CH 31 58 CH 33 47 20 33 109 to -1 600

Sub-humid L2 GM 1 12 CL 8 48 CH 53 55 CH 45 67

L3 GM NP 14 CL 4 46 CH 38 63 CH 40 50

L4 CH 29 60 CH 29 60 CH 29 60 CH 29 60

5 Goodfellow AFB San Angelo, TX Semi-arid L1 2 14 SC 10 36 CH 30 88 CL 28 87 >50 16 111 to 1 2000

L2 SC 11 38 CH 33 91 CH 30 91

L3 SC 9 37 CH 30 88 CL 28 90

L4 CH 32 84 CL 22 78 CL 22 78

6 South Plains AFB Lubbock, TX Dry L1 1.5 8 GM 7 11 CL 14 55 CL 18 55 80 17 108 to -17 3200

Sub-humid L2 GM 3 15 CL 11 54 CL 17 54

L3 GM NP 10 CL 14 54 CL 18 56

L4 CL 16 62 CL 16 62 CL 16 62

7 Memphis MA Memphis, TN Humid L1 3 9 GC 16 16 CL 14 83 CL 17 80 Near Sf 51 106 to -9 275

L2 GC 9 6 ML 7 82 CL 20 66

L3 GC 13 7 ML 5 89 CL 12 84

L4 CL 9 92 CL 9 92 CL 9 92

8 Keesler AFB Biloxi, MS Humid L1 2 9 GW NP 10 SW NP 5 SW NP 5 3 to 6 76 104 to 1 10

L2 GW NP 8 SW NP 5 SW NP 2

L3 SW NP 12 SW NP 2 SW NP 0

L4 SW NP - SW NP - SW NP -

9 WES Test Strip Vicksburg, MS Humid L1 2 9 SC 4 12 CL 20 100 CL 20 100 >100 52 104 to -1 200

L2 SC 4 12 CL 19 100 CL 20 100

L3 SC 4 12 CL 20 100 CL 20 100

L4 CL 20 98 CL 21 100 CL 20 100

10 Craig AFB Selma, AL Humid L1 1.5 9 SC 14 17 SM 3 37 SM 4 45 7 50 106 to -5 150

L2 SC 14 17 SM 3 37 SM 4 45

L3 SC 14 17 SC 10 37 SM 4 45

L4 SM 3 45 SM 3 45 SM 4 45

11 Vicksburg MA Vicksburg, MS Humid L1 1.5 9 GC 11 12 ML 3 98 ML 5 - 5.5 52 104 to -1 99L3 GC 11 12 ML 3 98 ML 5 -L4 ML - - ML - - ML - -

Site

Runw

ayRu

nway

Runw

ayRu

nway

Taxiw

ayTu

rnab

out

Taxiw

ayRu

nway

Runw

ayRu

nway

Runw

ay

StructureSubgrade-Comp. Subgrade-Nat.Sampling Base Course Sub-base

Thornthwaite Moisture Index Zone Class No TMI Material

1 -49 Base Material(Kirtland) Compacted Subgrade

Natural Subgrade

2 -35 Base Material(Goodfellow) Compacted Subgrade

Natural Subgrade

3 -32 Base Material(Santa Fe) Compacted Subgrade

Natural Subgrade

4 -24 Base Material(Clovis) Compacted Subgrade

Natural Subgrade

5 -19 Base Material(South Plains) Compacted Subgrade

Natural Subgrade

6 -8 Base Material(Bergstrom) Subbase Material

Compacted Subgrade

Natural Subgrade7 35 Base Material

(Vicksburg) Compacted Subgrade


(Memphis) Compacted Subgrade


(Craig) Compacted Subgrade


(WES) Compacted Subgrade


(Keesler) Compacted SubgradeNatural Subgrade

Dry

Sub

-hum

id

(0

> T

MI >

-20)

Hum

id

(TM

I > 2

0)

Arid

and

Sem

i-arid

(TM

I < -2

0)

Climatic data collected from NCDC

Kirtland Air Force Base / Albuquerque WB AP Station

Elevation (ft) 5,314 Latitude 35°02'60" Longitude 106°36'60"

Mean Monthly Temperature (F) Annual

Mo./Yr. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average

1944 29.2 40.0 44.4 52.2 63.9 73.3 76.4 76.3 68.6 58.7 43.0 36.3 55.2

1945 36.8 43.0 45.0 52.3 66.2 72.6 78.4 78.2 70.6 58.6 45.2 33.4 56.7 :

1957 39.9 48.1 47.3 54.2 61.9 74.8 79.1 76.0 70.3 56.6 40.3 38.5 57.3

1958 35.3 43.5 42.8 53.0 68.6 78.5 79.6 78.9 69.2 56.9 46.0 41.5 57.8 Monthly Precipitation (in) Total

1944 0.46 0.42 0.49 0.91 0.57 0.85 1.58 1.44 0.65 0.86 0.56 0.76 9.55

1945 0.34 0.32 0.50 0.77 0.01 0.01 1.09 2.27 0.26 0.43 0.01 0.35 6.36 :

1957 0.78 0.59 0.52 0.38 0.35 0.04 2.48 1.32 0.00 2.59 1.24 0.32 10.61

1958 0.21 0.27 1.71 0.62 0.43 0.22 0.14 1.74 1.34 1.72 0.37 1.35 10.12

CL

OV

IS A

FB -

BA

SE C

OU

RSE

CL

OV

IS A

FB –

CO

MPA

CT

ED

SU

BG

RA

DE

CL

OV

IS A

FB –

NAT

UR

AL

SUB

GR

AD

E

Nat

ural

Sub

grad

e C

ompa

cted

Sub

grad

e B

ase

Cou

rse

Top of Base Course

Kirtland AFB, New Mexico

Top of Subgrade


Into the Subgrade


Near Pavement Intermediate Near PavementCenter Line Location Edge

n 257 226 251ealg -27% -24% -6%eabs 34% 34% 21%

734Total Number of Data Points Analyzed

Parameter

735 datapoints – 11 airfields

part I: conclusions

Less error in predictions were observed near the pavement edge

Better predictions were obtained for subgrade materials

Evaluation, adjustment and calibration of EICM models to accommodate for airfield pavements will be needed

2-D water flow analysis will be necessary to improve predictions

Results suggest EICM model has potential to be adapted and

incorporated in airfield pavements design

The primary factor driving the selection of in-situ strength must

be governed by the site environmental conditions along

with the location of the groundwater table at the design

site location

The development and eventual implementation of the proposed

enhanced methodology, that would lead to a more accurate estimate of the in-situ strength, could provide significant economic benefits and cost savings to airfield pavement

design, evaluation and rehabilitation studies all over the world.

study 3 Impact of site location and groundwater table depth on the thickness of flexible airfield pavements

part I: introduction

Environmental effects on pavement design and performance is a fundamental component of any Mechanistic-Empirical Pavement Design procedure.

However, current airfield design procedures do not consider the effects of groundwater table depth and the effect due to environmental conditions.

There is a significant need to incorporate the influence of environmental site factors and the groundwater table depth upon flexible airfield pavement design and performance.

A methodology and computer code was developed at Arizona State University that allows for this analysis, including special considerations for unsaturated regions.

part II: objective of the study

Provide a quantitative assessment of the potential benefits and savings in pavement design thickness that occur due to the inclusion of specific environmental site properties

Environmental site properties analyzed included moisture, temperature and groundwater table depth

http://www.state.gov/video/?videoid=60761567001

The study focuses upon the prediction of pavement thickness to guard against excessive shear deformations or rutting for asphalt pavements.

Analysis was provided for a series of aircraft types, subgrade support values, different geographic locations across the US, and a range of GWT depths.

part III: the analysis

5 different climatic conditions

3 subgrade soils

6 groundwater table depths

Experimental Matrix 2 levels of design traffic

3 aircraft types

540 simulations

This study used the Limiting Subgrade Strain criteria developed for the newly revised USACE-β approach.

The Limiting Subgrade Strain criteria is a performance criteria applicable to design for excessive shear deformations (rutting) of the pavement.

The USACE limiting strain criteria is expressed as follows:

Input Needed

Material Properties and Structure

Layer Number 1 2 3 4 Material Type Asphalt Base Subbase Subgrade Thickness (in) 6.0 14.0 Variable Semi-Infinite Poisson Ratio 0.35 0.40 0.45 0.45 Elastic Modulus (ksi) 300 38 32 20 10 5

AASHTO Classification -- A-1-b A-2-4 A-4 A-6 A-7-6

Passing #200 (%) -- 17 22 60 70 80 Plasticity Index , PI -- 1.5 4 6 14 28 Specific Gravity, Gs -- 2.65 2.68 2.68 2.69 2.68 wopt % -- 8 14 12 15 20 γd max (pcf) -- 130 115 119 114 102

part IV: the software

Daniel Rosenbalm

Claudia E. Zapata

Carlos Cary Matthew Witczak

ZAPMEDACA Ramadan Salim

Mena Souliman

ZAPMEDACA

This program is an educational software program for the analysis of asphalt highway and airfield pavement structures

The program computes stress, strains, and displacements within the pavement structure from an enhanced application of Odemark’s transformation theory of layered systems

Pavement responses are computed by numerical integration of the Boussinesq solution

ZAPMEDACA

Program evaluates any multi-tire configuration of wheel loads

Each tire can be modeled by a circular, rectangular or elliptical wheel load and can be treated with either a uniform or non-uniform contact pressure

ZAPMEDACA

The most significant capability of the program is its ability to incorporate actual site environmental factors and GWT depth to characterize real time effect of partially saturated to saturated conditions/response of all unbound layers

For each design option, five main modules exist:

Load Configuration

Traffic Analysis

Pavement Structure

Environmental Effects

Stress Analysis

Main Module

18 KSAL Highway Approach

User Defined Critical Vehicle Gear

USACE Airfield Design (Revised)

Main module

Load Configuration

Pavement Structure and Material Properties

Traffic library

Traffic Input

Environmental effects

Location Longitude (decimal)

Latitude (decimal) TMI

Athens-GA -83.20 33.57 32.60 Cleveland-OH -81.51 41.24 41.65

Dallas-TX -97.02 32.54 -1.89 Los Angeles-CA -118.25 33.56 -31.62 McAlester-OK -95.54 34.54 2.51

Miami-FL -80.19 25.49 17.32 Orlando-FL -81.19 28.26 18.63 Phoenix-AZ -112.07 33.45 -54.95

Portland-ME -70.18 43.38 59.31 Raleigh-NC -78.47 35.52 37.52 Salem-OR -123.00 44.55 50.84

Seattle-WA -122.19 47.28 40.57 Shreveport-LA -93.49 32.27 31.84

Environmental effects

Stress Analysis

Vertical subgrade strain criteria

Rutting Design Criteria

part IV: the results

Resulting subgrade modulus after considering the environmental effects for 5 cities

Cost savings are proportional to savings of subbase thickness

Subbase thickness (in) for selected aircrafts

Required subbase thickness (in) for Boeing B737-600

Required subbase thickness (in) for Airbus A300-C4

Required subbase thickness (in) for Boeing B747-400 N = 100,000

Required subbase thickness (in) for Boeing B747-400 N = 1’000,000

part V: summary and conclusions

ZAPMEDACA software/program is a powerful analytical tool that incorporates environmental effects in airfield design

This has not been accomplished by any other airfield pavement design procedure used in the world!!

Savings of subbase material up to 2.5 feet for lighter B-737 aircraft to as much as 3 to 8 feet for heavier B-747 aircraft may occur when unsaturated soil mechanics / environmental conditions are incorporated in the pavement design process.

Savings are obvious when design thicknesses are compared to those obtained with the classical assumption used in most pavement design methods that rely upon fully soaked evaluation of all unbound material layers.

Results generated from this study provide quantitative evidence of the significant savings that may be accrued in the design, construction and rehabilitation of airfield pavements by using unsaturated soil mechanics principles in the design methodologies

part VI: recommendations

Several major additions need to be made to enhance ZAPMEDACA: Consider a wider range of computational

improvements

Additional distress types

Real time environmental model changes in unbound layers for flexible airfield pavement systems

Addition of the latest FAA criterion (FAARFIELD)

Controlled full-scale field tests to validate the results of ZAPMEDACA analysis are necessary but the analysis is valid for any climatic condition

International airfield pavement design agencies responsible for airfield operation should carefully re-evaluate the current state of the practice and move to incorporate more precise and rational theories and methodologies

part VII: acknowledgments

I would like to acknowledge the general guidance, valuable input and recommendations given by Prof. Matt Witczak, the data provided by Dr. Ray Rollings, and to my former PhD student and co-author, Dr. Carlos Cary.

part VIII: muchas gracias!

examples of use of climatic model on the design of flexible … 8 - site... · california bearing...

Documents